Centrifugal pump

ABSTRACT

Embodiments of the disclosure include a centrifugal pump assembly including a pump housing defining a cavity and an impeller disposed within the cavity, the impeller being affixed to a shaft. The pump housing includes an inner surface having a geometric pattern configured in increase a turbulence of a fluid flow over the inner surface. The impeller includes one or more blades and a shroud. The inner surface of the pump housing and the shroud of the impeller define a leakage path.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application claims priority to U.S. Provisional PatentApplication Ser. No. 61/676,024 filed on Jul. 26, 2012 which is herebyincorporated herein by reference in its entirety.

FIELD OF THE INVENTION

Exemplary embodiments of the present invention relate to a pump assemblyand, more particularly, to a centrifugal pump assembly with increasedefficiency.

BACKGROUND

Shaft driven centrifugal pumps are often used for cooling of automotiveengines. Centrifugal pumps operate by having water, or other fluid,directed axially into the pump and exit radially into one or morevolutes. The shaft is typically mechanically driven, directly orindirectly by the engine crankshaft, and therefore rotates at some speedproportional to engine speed. Generally, centrifugal pumps include animpeller that rotates in a pocket. The impeller includes a shroud thatis attached to the edge of the impeller vanes to help route the flow offluid from a low pressure region at the pump's center to the highpressure region at the pump's outer perimeter.

Typically centrifugal pumps include a pump cavity that is located inclose proximity to the shroud and a resulting leak path between the pumpcavity and the shroud. The hydraulic efficiency of the pump issubstantially affected by the clearance between the shroud and the pumpcavity due to the leakage flow at this interface. Accordingly, theclearance between the shroud and the pump cavity is usually minimized.However, manufacturing tolerances place limits on the extent by whichthe clearance can be minimized.

In general, the design of the pump affects the efficiency of the pump.An increase in pump efficiency means less power is consumed in drivingthe pump, and can result in improved fuel economy. In addition, lessthan ideal fluid flow in the pump can result in flow separation in theflow field, which reduces pump capacity and may cause unwanted pumpnoise due to cavitation.

SUMMARY OF THE INVENTION

In an exemplary embodiment, a centrifugal pump assembly includes a pumphousing defining a cavity. The pump housing includes an interior surfacehaving a geometric pattern configured to increase turbulence of thefluid flow over the interior surface. The centrifugal pump assembly alsoincludes an impeller disposed in the cavity, the impeller including oneor more blades and a shroud. The centrifugal pump assembly furtherincludes a shaft affixed to the impeller. The interior surface of thepump housing and the shroud of the impeller define a leakage path.

In another exemplary embodiment, a centrifugal pump assembly includes apump housing defining a cavity, wherein the pump housing includes aninterior surface. The centrifugal pump assembly also includes animpeller having one or more blades and a shroud disposed in the cavity.The centrifugal pump assembly also includes a shaft affixed to theimpeller. The interior surface of the pump housing and an exteriorsurface of the shroud of the impeller define a leakage path. At leastone of the interior surface of the pump housing and the exterior surfaceof the shroud include a geometric pattern configured to maximize aturbulence of a fluid flow in the leakage path.

The above features and advantages, and other features and advantages ofthe present invention are readily apparent from the following detaileddescription of the invention when taken in connection with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, features, advantages and details appear, by way ofexample only, in the following detailed description of the embodiments,the detailed description referring to the drawings in which:

FIG. 1 is a cross sectional side view of a centrifugal pump assembly;

FIG. 2 is a plan view of a pump housing of the centrifugal pump assemblyof FIG. 1; and

FIG. 3 a cross sectional side view of a centrifugal pump assembly inaccordance with an exemplary embodiment;

FIG. 4 is a perspective view of an pump housing in accordance with anexemplary embodiment;

FIG. 5 is a plan view of a pump housing in accordance with anotherexemplary embodiment; and

FIG. 6 is a plan view of a pump housing in accordance with a furtherexemplary embodiment.

DESCRIPTION OF THE EMBODIMENTS

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application or uses. It shouldbe understood that throughout the drawings, corresponding referencenumerals indicate like or corresponding parts and features.

Referring now to FIG. 1, a centrifugal pump assembly 100 is shown. Thecentrifugal pump assembly 100 includes a pump housing 110, whichincludes a cavity 112 and one or more volutes 114. In addition, thecentrifugal pump assembly 100 includes a rotatable shaft 104 and a seal106 that prevents fluid from passing out of the cavity 112 past theshaft 104. The centrifugal pump assembly 100 further includes animpeller 120 disposed inside of the cavity 112 such that the shaft 104extends through an aperture 122 of the impeller 120. The impeller 120 isfit onto the shaft 104 for rotation with the shaft 104. The impeller 120includes blades 124 and a shroud 126. The shroud 126 is affixed to theimpeller 120 and is configured to rotate with the impeller 120. Theshroud 126 of the impeller is disposed adjacent to an interior surface116 of the cavity 112. The separation of the shroud 126 and the interiorsurface 116 of the cavity 112 define a leakage path 140. The hydraulicefficiency of the pump is substantially affected by the fluid flow inthe leakage path 140. Accordingly, the clearance between the shroud 126and the interior surface 116 of the cavity 112 has typically beenminimized to minimize the fluid flow through the leakage path 140.Typically, as best illustrated by FIG. 2, the interior surface 116 has agenerally smooth surface.

In exemplary embodiments, the interior surface 116 of the cavity 112includes a geometric pattern that is configured to increase theturbulence of a fluid flow in the leakage path 140. By increasing theturbulence of the fluid flow through the leakage path 140, the volume offlow through the leakage path can be reduced and the volumetricefficiency of the pump 100 can be increased. In exemplary embodiments,the geometric pattern added to the interior surface 116 of the cavitydoes not result in a decrease in a required minimum physical separationbetween the shroud and the interior surface of the cavity. In exemplaryembodiments, a wide variety of different geometries can be used toincrease the turbulence of a fluid flow in the leakage path.

Referring now to FIG. 3, a cross-section of a centrifugal pump assembly200 in accordance with an exemplary embodiment is shown. The centrifugalpump assembly 200 is a shaft driven, centrifugal automotive water pump,but the invention as claimed is not limited to such. The centrifugalpump assembly 200 includes a pump housing 210, which includes a cavity212 and one or more volutes (not shown). In addition, the centrifugalpump assembly 200 includes a rotatable shaft 204 and a seal 206 thatprevents fluid from passing out of the cavity 212 past the shaft 204.The centrifugal pump assembly 200 further includes an impeller 220disposed inside of the cavity 212 such that the shaft 204 extendsthrough an aperture 222 of the impeller 220. The impeller 220 is fitonto the shaft 204 for rotation with the shaft 204. The impeller 220includes blades and a shroud 226. The shroud 226 is affixed to theimpeller 220 and is configured to rotate with the impeller 220. Theshroud 226 of the impeller 220 is disposed adjacent to an interiorsurface 216 of the cavity 212. The separation of the shroud 226 and theinterior surface 216 of the cavity 212 define a leakage path 240.

In exemplary embodiments, the interior surface 216 of the cavity 212includes a geometric pattern 230. In exemplary embodiments, thegeometric pattern 230 may include a wide variety of different geometriesthat are configured to increase the turbulence of a fluid flow in theleakage path 240. By increasing the turbulence of a fluid flow in theleakage path 240 the volume of flow through the leakage path can bereduced and the hydraulic efficiency of the pump can be increased. In analternative exemplary embodiment, the geometric pattern configured toincrease the turbulence of a fluid flow in the leakage path 240 may bedisposed on an exterior surface of the shroud 226 adjacent to theinterior surface 216 of the cavity 212. In yet another exemplaryembodiment, geometric patterns configured to increase the turbulence ofa fluid flow in the leakage path 240 may be disposed on both theexterior surface of the shroud 226 and the interior surface 216 of thecavity 212. In exemplary embodiments, the geometric pattern of theinterior surface 216 of the cavity 212 and the shroud 226 form alabyrinth seal. In general, labyrinth seals provide non-contact sealingby limiting the passage of fluid through chambers by the formation ofcontrolled fluid vortices that result from flow over sharp edgeconditions or through a torturous path.

Referring now to FIG. 4, a pump housing 310 in accordance with anexemplary embodiment is shown. As illustrated, the interior surface 316includes a geometric pattern 330 configured to increase the turbulenceof a fluid flow across the interior surface 316. In exemplaryembodiments the geometric pattern 330 may include a series of sharpedges in the form of concentric ribs 332 that project upwards toward theshroud of the impeller. In exemplary embodiments, the sharp edges of theribs 332 cause the leakage flow to locally separate from each cornerwhich limits the effective flow cross-sectional area and thus reducesthe extent of leakage flow.

Referring now to FIG. 5, a pump housing 410 in accordance with anotherexemplary embodiment is shown. As illustrated, the interior surface 416includes a geometric pattern 430 configured to increase the turbulenceof a fluid flow across the interior surface 416. In exemplaryembodiments the geometric pattern 430 may include a series of concentriclabyrinth rings 432 that are attached to form a screw that projectupwards toward the shroud of the impeller. In exemplary embodiments, thetop edges of the rings 432 cause the leakage flow to locally separatefrom each corner which increases limits the effective flowcross-sectional area and thus reduces the extent of leakage flow.

Referring now to FIG. 6, a pump housing 510 in accordance with a furtherexemplary embodiment is shown. As illustrated, the interior surface 516includes a geometric pattern 530 configured to increase the turbulenceof a fluid flow across the interior surface 516. In exemplaryembodiments the geometric pattern 530 may include a plurality ofprotrusions 532 that project upwards toward the shroud of the impeller.In exemplary embodiments, the protrusion 532 may have a stepped shape asillustrated or may have a smooth surface. In exemplary embodiments, theprotrusions 532 cause the leakage flow to be locally redirected at eachprotrusion 532 which increases the length of flow path and resultingpressure drop and thus reduces the extent of leakage flow. In exemplaryembodiment, the plurality of protrusions 532 may be arranged in a widevariety of configurations and each of the plurality of protrusions 532may have a wide variety of shapes. For example, the protrusions 532 mayhave a hemi-spherical shape, a pyramid shape, a conical shape, or anyother suitable shape. In exemplary embodiments the arrangement and shapeof the plurality of protrusions 532 on the interior surface 516 may beoptimized to maximize the turbulence induced by the protrusions 532 on afluid flow over the interior surface 516.

It will be appreciated by those of ordinary skill in the art that thegeometries disposed on the interior surface of the cavity illustrated inFIGS. 4-6 are provided for exemplary purposed only and that scope ofthis disclosure is not intended to be limited to the geometriesillustrated.

In exemplary embodiments, by increasing the turbulence of a fluid flowin the leakage path of the centrifugal pump assembly the efficiency ofthe centrifugal pump can be increased. For example, by reducing thefluid flow in the leakage path the amount of fluid flow through thevolutes can be increased without requiring additional power to operatethe pump. While the reduction of leakage flow may improve the pump'svolumetric efficiency, it also has the potential of adversely affectingits mechanical efficiency. However, it has been found that theimprovement in volumetric efficiency is greater that the loss inmechanical efficiency and thus the overall hydraulic efficiency may beimproved by 1-2%.

In exemplary embodiments, the pump housing may be cast aluminum and thegeometric pattern may be formed either during the casting process or maybe machined into the interior surface of the pump housing after the pumphousing is cast. In other exemplary embodiments, the pump housing may bemade of a composite material and the geometric pattern is formed on theinterior surface of the pump housing during the fabrication process.

While the invention has been described with reference to exemplaryembodiments, it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiments disclosed as the best modecontemplated for carrying out this invention, but that the inventionwill include all embodiments falling within the scope of the presentapplication.

What is claimed is:
 1. An centrifugal pump assembly comprising: a pumphousing defining a cavity, wherein the pump housing comprises aninterior surface having a geometric pattern configured in increase aturbulence of a fluid flow over the inner surface; an impeller disposedin the cavity, wherein the impeller comprises one or more blades and ashroud; and a shaft affixed to the impeller; wherein the interiorsurface of the pump housing and the shroud of the impeller define aleakage path.
 2. The centrifugal pump assembly of claim 1, wherein thegeometric pattern includes a series of concentric ribs.
 3. Thecentrifugal pump assembly of claim 1, wherein the geometric patternincludes a series of concentric labyrinth rings.
 4. The centrifugal pumpassembly of claim 1, wherein the geometric pattern includes a pluralityof protrusions that project towards the shroud.
 5. The centrifugal pumpassembly of claim 4, wherein the plurality of protrusions have ahemi-spherical shape, a pyramid shape, or a conical shape.
 6. Thecentrifugal pump assembly of claim 1, wherein the geometric pattern isconfigured to maximize a turbulence of a fluid flow in the leakage path,wherein an increase in the turbulence of the fluid flow in the leakagepath results in a reduction of a volume of the fluid flow.
 7. Ancentrifugal pump assembly comprising: a pump housing defining a cavity,wherein the pump housing comprises an interior surface; an impellerdisposed in the cavity, wherein the impeller comprises one or moreblades and a shroud; a shaft affixed to the impeller; wherein theinterior surface of the pump housing and an exterior surface of theshroud of the impeller define a leakage path; and wherein at least oneof the interior surface of the pump housing and the exterior surface ofthe shroud include a geometric pattern configured to maximize aturbulence of a fluid flow in the leakage path, wherein an increase inthe turbulence of the fluid flow in the leakage path results in areduction of a volume of the fluid flow.
 8. The centrifugal pumpassembly of claim 7, wherein the geometric pattern includes a series ofconcentric ribs.
 9. The centrifugal pump assembly of claim 7, whereinthe geometric pattern includes a series of concentric labyrinth rings.10. The centrifugal pump assembly of claim 7, wherein the geometricpattern includes a plurality of protrusions that project towards theshroud.
 11. The centrifugal pump assembly of claim 7, wherein the pumphousing is formed by casting aluminum and the geometric pattern isformed during the casting process.
 12. The centrifugal pump assembly ofclaim 7, wherein the pump housing is formed by casting aluminum and thegeometric pattern is formed by machining the pump housing.